With the continuing development of and advances in power line communications technologies, it is expected that power line communications (“PLC”) systems eventually will be installed on electric power distribution networks or grids existing throughout the world.
It is well known in the art that an electric power distribution network, which is composed of conventional electric power lines and wires and associated power transformer equipment, can operate to convey electricity along the electric lines and wires having voltages from about 90 VAC to 20 KVAC and frequencies from about 40 Hz to 400 Hz. The physical communications protocol layer component of PLC transmitter and receiver devices that form a PLC system, therefore, must operate in relation to the ranges of voltages and frequencies associated with the electric power distribution network on which the PLC devices are installed to ensure that communication over the PLC network is maintained robust.
In current PLC transmitter and receiver devices, the physical communication protocol layer is designed to operate according to the characteristics of the electric power distribution network for which installation of the PLC device is planned. In some PLC transmitter and receiver device implementations in areas of the world where the physical network topology is small in size and relatively free of communication impairments, a high degree of spectral containment is desirable, in other words, PLC transmissions desirably occur utilizing the maximum available spectrum and also the maximum possible length of PLC transmission, which is commonly referred to as the symbol length. In other PLC transmitter and receiver device implementations, the PLC transmissions need to occur in the presence of impairments to communications, such as multi-path fading or reflections that place limitations upon the maximum available symbol length. In many current PLC system implementations, the PLC devices operate in accordance with standard OFDM communication principles conventional in the art, such as those included in the HomePlug 1.0 communications standard specification, which is incorporated by reference herein. Still other PLC transmitter and receiver device implementations need to provide for compatibility with existing or legacy PLC equipment that operate in accordance with different communications protocol requirements.
Therefore, there exists a need for a low cost physical communications protocol layer architecture for inclusion in a PLC transmitter and/or receiver device which provides for dynamic selection of a mode of communications signal transmission operation from a plurality of communications signal transmission operation modes to make the PLC device compatible with a plurality of PLC communications protocol requirements and also the characteristics of the electric power distribution network on which the PLC device is installed.